Optimal Body Weight Workout?

This year I have been doing only body weight exercises. I'd like to keep doing so, but I want to reduce the time required. It would be great to exercise once a week or less frequently, as Dave tells.

Now I am following the Primal Blueprint fitness, with pushups, squats, pullups and planks. Excercise are varied while I get stronger. The problem is it takes an hour to do all of them and Mark Sisson suggests to do them twice a week.

Any suggestion on how to reduce the time and the frequency but keep the results?